The present invention relates to nasal masks for use with continuous positive airway pressure (CPAP) systems. More particularly, it relates to a mask worn over the nose of a patient, such as an infant, when receiving nasal CPAP therapy.
Continuous positive airway pressure (CPAP) therapy has been employed for many years to treat patients experiencing respiratory difficulties and/or insufficiencies. More recently, CPAP therapy has been advanced as being useful in assisting patients with under-developed lungs (in particular, infants and especially premature infants or neonates), by preventing lung collapse during exhalation and assisting lung expansion during inhalation.
In general terms, CPAP therapy entails the continuous transmission of positive pressure into the lungs of a spontaneously breathing patient throughout the respiratory cycle. A CPAP system generally includes a CPAP generator adapted to create or generate a continuous positive airway pressure within one or two tubes, along with a patient interface device connected to the generator that serves as a conduit for transfer of inhaled and exhaled gases. The CPAP system can assume a variety of forms, including a fixed flow, ventilator-type system, or a variable flow system.
CPAP can be delivered to the patient using a variety of patient interface devices, for example an endotracheal tube. With infants, however, it is more desirable to employ a less invasive patient interface device, in particular one that interfaces directly or indirectly with the nasal airways via the patient's nares. Such systems are commonly referred to as nasal continuous positive airway pressure (nCPAP) systems.
With nCPAP systems, the patient interface piece is typically either a dual prong body or a mask. The dual prong device includes two prongs or cannulas each sized for insertion within a respective nare of the patient. While a relatively stable fluid seal can readily be accomplished between the prongs and the nasal airways, some patients, especially infants, negatively react to the discomfort attendant with insertion of the prongs. Conversely, the nasal mask device is placed over the patient's nose and thus, in theory, will cause less patient discomfort. Unfortunately, currently available infant nCPAP masks have several shortcomings.
For example, available nCPAP masks are only somewhat flexible (especially relative to a point of interface with the CPAP system) and thus cannot accommodate any misalignment of the nCPAP generator relative to the patient's nose. When the nCPAP generator is later moved relative to the patient to correct this misalignment, the nCPAP mask will also move in a similar fashion, potentially leading to air leaks relative to the patient's face or general patient discomfort. This can be especially problematic with infants whom otherwise have small facial features and thus less available surface area for achieving and maintaining a fluid tight seal with the mask.
Along these same lines, it is oftentimes necessary to apply a fairly significant force to the nasal mask to ensure a fluid tight seal against the patient's nose/face. For example, a strap is commonly wrapped about the patient's head and connected to the CPAP generator. The CPAP generator, in turn, is assembled to the nasal mask such that a force placed on the CPAP generator by the strap is transferred onto the nasal mask in sealing the mask about the patient's nose. Because the conventional nasal mask may not readily conform to the contours of the patient's facial anatomy, the strap must be pulled tight so as to maintain the desired, fluid-tight seal. For certain patients, especially infants, this securing force can cause great discomfort, cause bruising and lead to skin necrosis. Also, the forces may be concentrated by the mask at a few pressure points on the patient's nose/face, further increasing the likelihood of long-term complications (e.g., sores or wounds on the patient's nasal septum, upper lip, nasal bridge, cheeks, etc.). Along these same lines, perhaps in an effort to promote complete contact with the patient's face, conventional nasal mask designs intimately contact the patient's upper lip directly at and below the nasal septum exterior. For many infants, the skin of the upper lip philtrum is delicate and highly sensitive, and can more easily succumb to necrosis when contacted by the mask. Regardless, an infant patient will react quite negatively to even minor discomfort associated with application of the nasal mask to his or her nose/face.
In light of the above, a need exists for an improved nasal mask for use with an nCPAP system, especially for infant patient applications.